Vibration resistant switch employing contacts with different resonant frequencies



Nov. 16, 1965 P. G. SALERNO VIBRATION RESISTANT SWITCH EMPLOYING CONTACTS WITH DIFFERENT RESONANT FREQUENCIES Filed Feb. 1.7, 1964 FlC5.6

INVENTOR.

G. SALERNO ham A PAUL United States Patent 3,218,424 VIBRATION RESISTANT SWITCH EMPLOYING CONTACTS WITH DIFFERENT RESONANT FREQUENCIES Paul G. Salerno, Glenview, Ill., assignor to Vapor Corporation, Chicago, 111., a corporation of Delaware Filed Feb. 17, 1964, Ser. No. 345,353 2 Claims. (Ci. 200155) This invention relates in general to a switch for opening and closing electrical circuits, and more particularly to a switch that obviates malfunctioning normally caused by vibration.

The switch of the present invention includes contacts that are spring mounted to increase their contacting eificiency when brought into engagement with stationary contacts. Particularly, the contacts are of the typical double break type or double pole type, although the invention may have other uses and purposes. Heretofore, a switch of this type, when closed and subjected to a vibration of a frequency equal to the resonant frequency of the contacts and spring, would open at inopportune times which is quite undesirable. In the present invention, this is overcome by splitting the contacts and individually mounting them on springs so that each split portion and its accompanying spring will have a different resonant frequency, and in this situation only one of the split portions might open but have no effect on opening of the circuit.

Accordingly, it is an object of this invention to provide an improved switch that is not affected by vibration.

Another object of this invention is in the provision of a switch including a fixed support for one set of contacts and movable support for another set of contacts, and where the movable contacts are spring mounted so that upon closing of the contacts, the switch is unaffected by vibration.

Still another object of this invention resides in the provision of a switch having stationary contacts and movable contacts that are spring mounted in such a manner as to preclude the switch from opening upon being subjected to vibrations of any frequency.

Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheet of drawing, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a perspective view of a switch constructed in accordance with the present invention and shown in open position;

FIG. 2 is an exploded diagrammatic view of a set of contacts on one side of the switch of FIG. 1;

FIG. 3 is a perspective view of a set of movable contacts removed from the contact carriage in the embodiment of FIG. 1;

FIG. 4 is an end view of the contact assembly of FIG. 3;

FIG. 5 is a front elevational View of the contact assembly of FIG. 3 and shown in association with and in initial contact with a set of stationary contacts; and

FIG. 6 is a view similar to FIG. 5 but illustrating the flexing of the spring wherein the contact assembly is in fully closed position.

Referring now to the drawing and particularly to FIG. 1, one example of a switch is illustrated embodying the invention, wherein a contact carriage 10 includes a pair of contact supporting arms 11 and 12 on opposite sides for supporting sets of contacts 13 and 14, respectively. Any suitable drive means may be provided for driving the contact carriage 11 which in the embodiment shown moves by rotation.

3,218,424 Patented Nov. 16, 1965 'ice A set of stationary contacts 15 mounted on contact supporting means 16 is adapted to coact with the contacts 13, while a set of stationary contacts 17 mounted on a contact supporting means 18 is adapted to coact with the set of contacts 14. Thus, the contacts 13 and 14 may be termed movable and are driven into and out of engagement with the fixed or stationary contacts 15 and 17 by a power means connected to the contact carriage 10.

The set of contacts 15 includes a pair of spaced and insulatably separated contacts 15a and 15b, while the set of contacts 17 similarly includes a pair of spaced and insulatably separted contacts 17a and 17b. The contact supporting means 16 and 18 may be of insulated material, but in any case the individual contacts mounted thereon must be insulated from each other. The contacts 15a and 15b, respectively, are provided with terminals 19 and 20 which are adapted to have suitable wires connected thereto from a circuit. While not shown, contacts 17a and 17b are similarly provided with terminals for connection to a circuit. The contacts 17a and 17b may be connected to a circuit different from that connected to the contacts 15a and 15b, or they may be connected in parallel to the contacts 15a and 15b whereby closing of contacts 15 or 17 will serve to close the circuit.

Inasmuch as the movable contacts 13 and 14 are essentially identical, specific details of only one need be described to understand the invention, and accordingly reference will be hereinafter made to the set of contacts 13 in referring to FIGS. 26. A set of contacts 13 includes split portions 21 and 22, each of which may include an elongated bar 23 and 24 respectively, and contact pads 25 and 26, respectively. Above the split portion 21 and in sliding contact with its upper surface is a leaf spring 27, while a leaf spring 28 is arranged above the split portion 22. A bracket 29 is provided with inwar-dly bent end portions for connection to the contact supporting arm 11 of the contact carriage 10, while split portion supporting brackets 30 and 31 are secured to the bracket 29 and support the split portions 21 and 22 relative to the leaf springs 27 and 28. Rivets or other fasteners 32 and 33 secure the springs 27 and 28 and split portion supporting brackets 30 and 31 to the main bracket 29 as particularly seen in FIG. 4.

The bracket 30 includes legs 30:: and 3% with inwardly turned ends that hold the split portion against the leaf spring 27 while permitting the split portion to move toward and away from the bracket 29. Similarly, the bracket 31 includes legs 31a and 31b with inwardly turned ends for supporting the split portion 22 against the spring 28.

In operation, engagement of the contacts 13 with the contacts 15 is such that the contact pads 25 and 26 of the split portions 21 and 22 engage the contacts 15a and 15b. The split portions 21 and 22, being of an electrically conductive material, then close the circuit between the contacts 15a and 15b. The construction of the contacts 13 is such that the spring-mass combination of spring 27 and split portion 21 has a resonant frequency different from the spring-mass combination of spring 28 and split portion 22. Therefore, when the contacts 13 are in engagement with the contacts 15, and thereafter subjected to the vibration of a frequency equal to the resonant frequency of one spring and split portion combination and thereby cause opening of same, the other spring and split portion combination, having a different resonant frequency, will remain closed. In order to differentiate the resonant frequency of the spring and split portion combinations, the leaf springs 27 and 28 may be chosen with different rates, or the split portions 21 and 22 may be chosen with different masses. In any event, both spring and split portion combinations cannot be in resonant vibration at the same time, and therefore no opening or breaking of the circuit connected to contacts 15a and 15b will occur. FIGS. 5 and 6 show the steps of engagement between the contacts 13 and 15, wherein the contacts are in initial engagement in FIG. 5 and in pressure engagement in FIG. 6.

While the embodiment of the drawings described herein relates to a double pole switch, it should be appreciated that the invention may be applied to a single pole switch, or any switch that may be subjected to vibration and having at least one contact spring mounted.

A further embodiment would involve only a single contact bridge and leaf spring mounted on each of the contact supporting arms 11 and 12, and the parallel connection of the contacts 15a and 15b with contacts 17a and 17b so that upon closing of either the contacts 15 or 17, the circuit would be closed. In this arrangement, it can be appreciated that the contact bridge and spring on one of the contact supporting arms would have a spring-mass combination of a resonant frequency different from the contact bridge and spring on the other contact supporting arm. In such a situation, the contact bridge and spring on one contact supporting arm could not be in resonant vibration at the same time as the contact bridge and spring on the other contact supporting arm so that no opening of the circuit would occur when the switch is under vibration.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

The invention is hereby claimed as follows:

1. A switch comprising, first and second sets of contacts adapted to be selectively in engagement to open and close an electrical circuit, each of said sets of contacts being mounted on a support, one of said sets of contacts and corresponding support being movable toward and away from the other of said sets of contacts and corresponding support, one of said sets of contacts including a first pair of spaced contacts insulated from each other, the other of said sets of contacts including a second pair of spaced contacts adapted to mate with said first contacts, each of said second contacts being split to define therewith first and second sections, said first sections being mounted on a first electrically conductive bar and said second sections being mounted on a second electrically conductive bar, means for spring mounting each of said bars on the corresponding support, and the spring rate of one of said spring mounting means being greater than the other, whereby the spring-mass combination of one of the bars and spring mounting means has a resonant frequency different from the spring-mass combination of the other of said bars and spring mounting means.

2. A switch comprising, first and second sets of contacts adapted to be selectively in engagement to open and close an electrical circuit, each of said sets of contacts being mounted on a support, one of said sets of contacts and corresponding support being movable toward and away from the other of said sets of contacts and corresponding support, one of said sets of contacts including a first pair of spaced contacts insulated from each other, the other of said sets of contacts including a second pair of spaced contacts adapted to mate with said first contacts, each of said second contacts being split to define therewith first and second sections, said first sections being mounted on a first electrically conductive bar and said second sections being mounted on a second electrically conductive bar, means for spring mounting each of said bars on the corresponding support, and the mass of one bar being greater than the mass of the other bar, whereby the spring-mass combination of one of the bars and spring mounting means has a resonant frequency different from the springmass combination of the other of said bars and spring mounting means.

References Cited by the Examiner UNITED STATES PATENTS 2,077,622 4/ 1937 Field. 2,324,891 7/ 1943 Thumim 200166 X 2,421,267 5/ 1947 Huber 200166 X KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner, 

1. A SWITCH COMPRISING, FIRST AND SECOND SETS OF CON TACTS ADAPTED TO BE SELECTIVELY IN ENGAGEMENT TO OPEN AND CLOSE AN ELECTRICAL CIRCUIT, EACH OF SAID SETS OF CONTACTS BEING MOUNTED ON A SUPPORT, ONE OF SAID SETS OF CONTACTS AND CORRESPONDING SUPPORT BEING MOVABLE TOWARD AND AWAY FROM THE OTHER OF SAID SETS OF CONTACTS AND CORRESPONDING SUPPORT, ONE OF SAID SETS OF CONTACTS INCLUDING A FIRST PAIR OF SPACED CONTACTS INSULATED FROM EACH OTHER, THE OTHER OF SAID SETS OF CONTACTS INCLUDING A SECOND PAIR OF SPACED CONTACTS ADAPTED TO MATE WITH SAID FIRST CONTACTS, EACH OF SAID SECOND CONTACTS BEING SPLIT TO DEFINE THEREWITH FIRST AND SECOND SECTIONS, SAID FIRST SECTIONS BEING MOUNTED ON A FIRST ELECTRICALLY CONDUCTIVE BAR AND SAID SECOND SECTIONS BEING MOUNTED ON A SECOND ELECTRICALLY CONDUCTIVE BAR, MEANS FOR SPRING MOUNTING EACH OF SAID BARS ON THE CORRESPONDING SUPPORT, AND THE SPRING RATE OF ONE OF SAID SPRING MOUNTING MEANS BEING GREATER THAN THE OTHER, WHEREBY THE SPRING-MASS COMBINATION OF ONE OF THE BARS AND SPRING MOUNTING MEANS HAS A RESONANT FREQUENCY DIFFERENT FROM THE SPRING-MASS COMBINATION OF THE OTHER OF SAID BARS AND SPRING MOUNTING MEANS. 